JP2007059777A - Multilayered printed circuit board and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a conduction resistance value of a conductor that fills a through-hole in a double-faced board and copper foil, to improve reliability in connection between layers, and to prevent the breakage of a dielectric material. <P>SOLUTION: A multilayered printed circuit board 1 is constituted such that at least one sheet of single-sided boards 20, 30 is laminated one by one on both sides of the double-faced board 10, a conductor 18 is coated on the surface of the foil 12 around the through-hole 14 of the board 10, the coating range of the conductor 18 that coats the surface of the foil 12 is of a width w from the outer periphery of the through-hole 14 in the board 10 of 10-50 μm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a multilayer printed wiring board and a method for manufacturing the same.

  In recent years, electronic devices are becoming smaller and lighter in addition to high-frequency signals and digital signals. Accordingly, printed wiring boards mounted on electronic devices are also required to be downsized and mounted with high density. As printed wiring boards that meet these requirements, multilayer printed wiring boards are widely used. In particular, the batch lamination method is being developed because it has the advantage of reducing the number of manufacturing steps and the defect rate.

  Conventionally, as this type of multilayer printed wiring board, one in which a single-sided board having a copper foil is laminated on only one side of a board is mainly used. Moreover, what laminated | stacked the single-sided board collectively on the one side or both sides of the double-sided board which has copper foil on both surfaces of a board | substrate is also known.

Patent Document 1 includes an expanded portion in which a conductive paste filled in a through hole of a double-sided plate is expanded in a flange shape on a copper foil on the opening side of the through-hole, and single-sided plates are laminated on both sides of the double-sided plate. A multilayer printed wiring board is described.
Patent Document 2 describes a method of manufacturing a multilayer printed wiring board by laminating single-sided boards collectively on a double-sided plate in which through holes are filled with a conductive material.
In Patent Documents 3 and 4, for a method of manufacturing a multilayer printed wiring board by batch lamination, after etching the copper foil around the through hole into a groove shape or a gear type, the conductive material is filled into the through hole, The contact area between the conductive material and the copper foil is increased, and the electrical connection between the two is improved.
Patent Documents 5 to 12 describe a method of manufacturing a multilayer printed wiring board by filling a through hole of a copper clad laminate (CCL) after circuit formation with a conductive material by screen printing and laminating them at once.
Patent Document 13 describes a method of forming a uniform and thin film by filling a conductive material after masking a photosensitive resist having through holes.
JP 2004-221192 A JP 2004-363325 A JP 2003-338668 A JP 2004-014559 A JP 2002-353619 A JP 2002-353620 A JP 2002-353621 A JP 2002-353622 A Japanese Patent Laid-Open No. 2003-092469 JP 2003-092470 A JP 2003-092471 A Japanese Patent Laid-Open No. 2003-092473 JP 2003-309367 A

  The single-sided boards 110, 120, and 130 having the copper foils 112, 122, and 132 on one side of the insulating base materials 111, 121, and 131 as in the multilayer printed wiring board 100 and the manufacturing method thereof shown in FIGS. When stacked, the conductors 124 and 134 filled in the through holes 123 and 133 are in direct contact with the copper foils 112 and 122 over a wide area, so that the interlayer resistance value is low and the connection reliability is also good. Reference numerals 140 and 150 denote adhesive sheets.

  However, as in the multilayer printed wiring board 200 and the manufacturing method thereof shown in FIGS. 7 and 8, the double-sided board 210 having the copper foils 212 and 213 on both sides of the insulating base material 211, and the insulating base materials 221 and 231. After the through holes 214, 223, 233 are formed in each of the single side plates 220, 230 having the copper foils 222, 232 on one side, and the conductors 215, 224, 234 are filled in the through holes 214, 223, 233, the prior art When the single-sided plates 220 and 230 are collectively laminated on both sides of the double-sided plate 210, the conductive material 215 filled in the through-hole 214 of the double-sided plate 210 is copper having a thickness of several μm to several tens of μm on the side surface of the through-hole 214. Contact is made only at the cross section of the foil 213. For this reason, there exists a problem that the conduction resistance value of the front and back of the double-sided board 210 becomes high. Furthermore, there is a concern that the environmental resistance is inferior. Reference numerals 240 and 250 denote adhesive sheets.

  In the case of the configuration described in Patent Document 1, the conductive connection between the conductive paste in the through hole and the copper foil layer on the opening side of the through hole is an extension of the conductive paste in addition to the inner peripheral surface of the copper foil layer. And a relatively wide contact area between the upper surface of the copper foil layer (see paragraph 0032 of Patent Document 1). However, although it is not considered as a problem in the document 1, the conductive paste that forms the extended portion is a soft material compared to the insulating base material or copper foil that constitutes the substrate. There is a problem that the expansion portion is broken due to temperature change, pressurization, or the like. No countermeasure is shown in Patent Document 1 for this problem.

  In the case of the configuration described in Patent Documents 2 to 4, since the conductive material filled in the through hole and the copper foil cross section on the side surface of the through hole are in contact with each other and are electrically connected, the conduction resistance value on the front and back of the double-sided plate is The problem of being slightly higher is inevitable. Also, no countermeasures for this problem are shown.

Patent Documents 5 to 12 all relate to batch lamination of single-sided plates. That is, in these known documents, there is no document that mentions a problem related to the simultaneous lamination of double-sided boards.
Patent Document 13 relates to a method for filling a through hole with a conductive material, and does not include a description of electrical connection improvement in batch lamination of double-sided boards.

  The present invention has been made in view of the above circumstances, and reduces the conductive resistance between the conductive material filling the through hole of the double-sided plate and the copper foil, improves the connection reliability between the layers, and prevents the breakage of the conductive material. It is an object of the present invention to provide a multilayer printed wiring board and a method for manufacturing the same.

  In order to solve the above problems, the present invention is a multilayer printed wiring board in which at least one single-sided board is laminated on each side of a double-sided board, and is electrically conductive on the copper foil surface around the through hole of the double-sided board. Provided is a multilayer printed wiring board characterized in that a covering range of the conductive material is 10 to 50 μm in width from the outer periphery of the through hole of the double-sided board.

  The present invention also relates to a method for manufacturing a multilayer printed wiring board in which at least one single-sided board is laminated on each side of a double-sided board, and the covering area is on the copper foil surface around the through hole of the double-sided board. A multilayer printed wiring board characterized in that a conductive material is coated so as to have a width of 10 to 50 μm from the outer periphery of the through hole of the double-sided board, and then at least one single-sided board is collectively laminated on both sides of the double-sided board. A manufacturing method is provided.

  The present invention is also a method for producing a multilayer printed wiring board in which at least one single-sided board is laminated on each side of the double-sided board, and is located at a location facing the copper foil surface around the through hole of the double-sided board. After coating the conductive material around the through hole of the single-sided plate so that the covering area is 10 to 50 μm wide from the outer periphery of the through-hole of the single-sided plate, collect at least one single-sided plate on both sides of the double-sided plate A method for producing a multilayer printed wiring board is provided, wherein the conductive material is laminated and brought into contact with the copper foil surface around the through hole of the double-sided board.

  According to the present invention, the conductive material is coated on the surface of the copper foil around the through hole of the double-sided plate, and the coverage of the conductor on the surface of the copper foil is 10 to 50 μm wide from the outer periphery of the through hole. In addition to reducing the conduction resistance between the conductive material filling the through holes of the double-sided board and the copper foil and improving the connection reliability between the layers, the conductive material covering the surface of the copper foil is broken. Can be reliably prevented.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a partial cross-sectional view showing an example of the multilayer printed wiring board of the present invention. A multilayer printed wiring board 1 shown in FIG. 1 includes a double-sided board 10 having copper foils 12 and 13 on both sides of an insulating substrate 11, and a single-sided board having copper foils 22 and 32 on one side of the insulating bases 21 and 31. 20 and 30 are laminated, and adhesive sheets 40 and 50 are provided between the double-sided plate 10 and the single-sided plates 20 and 30 for adhesion. Each copper foil 12, 13, 22, 32 is formed with a circuit (not shown). The insulating base materials 11, 21, and 31 are not particularly limited as long as they are used in the field of printed wiring boards, and examples thereof include polyimide.

  In this embodiment, the first single-sided plate 20 is laminated on one side of the double-sided plate 10 and the second single-sided plate 30 is laminated on the other side of the double-sided plate 10. One or more other single-side plates may be laminated on one single-side plate 20 and / or the second single-side plate 30. When laminating the double-sided plate 10 and the single-sided plates 20 and 30, since the number of manufacturing steps and the defect rate can be reduced, a collective laminating method in which these three or more substrates are laminated together is preferable.

  Through holes 14, 23, 33 are formed in the insulating base materials 11, 21, 31 of the double-sided plate 10 and single-sided plates 20, 30 for interlayer conduction, and the through-holes 14, 23, 33 are formed. Is filled with conductive materials 15, 24, 34. In one copper foil 12 of the double-sided plate 10, an opening 16 having the same diameter as the through-hole 14 of the double-sided plate 10 is formed in order to form the through-hole 14 of the double-sided plate 10. On the other hand, small holes 17, 25, 35 having smaller diameters than the through holes 14, 23, 33 are formed in the copper foils 22, 32 of the single-sided plates 20, 30 and the other copper foil 13 of the double-sided plate 10. Has been.

  The first adhesive sheet 40 laminated between one copper foil 12 of the double-sided board 10 and the insulating base material 21 of the first single-sided board 20 has the through holes 14 of the double-sided board 10 and the copper foil 12. An opening 41 larger than the opening 16 is formed. Further, an opening 41 having the same diameter as the through hole 14 of the double-sided board 10 is formed. In addition, the second adhesive sheet 50 laminated between the other copper foil 13 of the double-sided plate 10 and the insulating base 31 of the second single-sided plate 30 includes the through hole 14 and the second of the double-sided plate 10. An opening 51 having the same size as the through hole 33 of the single-sided plate 30 is formed. The conductive materials 15, 24, 34 filled in the through holes 14, 23, 33 are also filled in the openings 16, 41, 51 and the small holes 17, 25, 35, and on the surface of one copper foil 12. The conductor 18 to be covered is in contact with the conductor filled in the through holes 14, 23, 33, and electrical connection between these conductors 15, 18, 24, 34 is ensured.

  The conductive materials 15, 24, 34 filled in the through holes 14, 23, 33 and the conductive material 18 covering the surface of one copper foil 12 are different from the copper foils 12, 13, 22, 32 in terms of types and properties. Are made of different materials. As the conductive materials 15, 18, 24, and 34 used for filling and coating, a material in which a binder is blended with a conductive material is preferable, and a highly viscous liquid, fluid liquid, paste, and the like in a temperature range where the multilayer printed wiring board 1 is used. Forms such as gels, waxes, and pastes are preferred. Specific examples of the material used as the conductive material include conductive materials such as copper (Cu), silver (Ag), and gold (Au), and conductive materials such as carbon, and acrylic resins and epoxy resins as binders for the conductive materials. Phenol resin, urethane resin, etc. are used. The shape of the conductive material (particle shape) is not particularly limited, such as a spherical shape or an indefinite shape. A plurality of kinds of conductive materials may be blended alone or in an alloy form.

  Furthermore, a material in which the binder of the conductive material itself has conductivity may be used as the conductive material. Typical examples of the conductive binder include metals and organic compounds such as polyacetylene, polyaniline, polypyrrole, and polythiophene. The conductor 18 covering the surface of one copper foil 12 may be made of the same material as the conductors 15, 24, 34 filled in the through holes 14, 23, 33 as shown in FIG. Further, as shown in FIG. 4, the material may be a different type from the conductive materials 15, 24, 34 filled in the through holes 14, 23, 33. In addition, as the conductive materials 15, 18, 24, and 34, a plurality of types of conductive materials may be mixed.

  Regarding the conduction between the copper foils 13, 22, 32 having the small holes 17, 25, 35 and the conductive materials 15, 24, 34 filled in the through holes 14, 23, 33, the diameters and the through holes of the small holes 17, 25, 35 are used. Due to the difference from the diameters of the holes 14, 23, 33, the conductors 15, 24, 34 are not only the cross-sections of the copper foils 13, 22, 32 that are the inner peripheral surfaces of the small holes 17, 25, 35, but also the small holes 17, The surfaces around 25 and 35 are also in direct contact with the copper foils 13, 22, and 32, and electrical conduction between the conductive materials 15, 24, and 34 and the copper foils 13, 22, and 32 is made in a large area.

  Further, regarding the conduction between one copper foil 12 of the double-sided board 10 and the conductive material, the conductive material 18 filled in the opening 41 of the first adhesive sheet 40 is copper around the through hole 14 of the double-sided board 10. The surface of the foil 12 is coated. For this reason, the conduction between one copper foil 12 of the double-sided board 10 and the conductors 15, 18 is not only in contact with the cross section of the copper foil 12 where the conductor 15 becomes the inner peripheral surface of the opening 16, but also through holes The conductive material 18 and the surface of one of the copper foils 12 are in direct contact with each other on the surface around 14, and electrical conduction is made in a large area. For this reason, a conduction resistance value can be reduced and long-term connection reliability can be improved.

  It is known that the linear expansion coefficient varies depending on the type of material constituting the substrate of the multilayer printed wiring board. Therefore, the volume change (dimensional change) of each constituent material varies depending on the temperature change. Therefore, when the outer periphery of the through hole 14 is used as a reference, a slightly larger covering range is required. If the conductor 18 is not sufficiently covered, contact failure or the like may occur in the conductor portion, and the electrical resistance may change. For this reason, in the present invention, the width w from the outer periphery of the through hole 14 of the double-sided board 10 is defined as at least 10 μm or more in the covering range of the conductive material 18.

In addition to this, a demerit occurs when the covering width of the conductive material 18 is too large. In general, the conductive material 18 serving as a coating material is a softer material than an insulating base material or copper foil constituting the substrate. For this reason, when a volume change (dimensional change) of each constituent material occurs due to a temperature change, the external force (stress) is applied to the covering conductive material 18, which may cause a coating tear. If the coating breaks, the portion cannot be protected, or there may be a problem of poor conduction with respect to the copper foil or the like. For this reason, in the present invention, the upper limit of the width w from the outer periphery of the through hole 14 of the double-sided plate 10 in the covering range of the conductive material 18 is defined as 50 μm.
In addition, the conduction failure due to the coating breakage can be verified by the conduction resistance value before and after the vapor phase thermal shock treatment described in the example column of this specification. Further, it can be verified by a known test method such as EIAJ ED4701 / 100 test method 102 “high temperature and high humidity bias test” of JEITA (Japan Information Technology Industry Association).

  That is, in the present invention, the covering range of the conductive material 18 covering the surface of one copper foil 12 of the double-sided board 10 is such that the width w from the outer periphery of the through hole 14 of the double-sided board 10 is in the range of 10 to 50 μm. It is characterized by that. As a result, it is possible to reduce the conductive resistance value between the conductive material 15 filled in the through hole 14 of the double-sided board 10 and the copper foils 12 and 13 of the double-sided board 10 and improve the connection reliability between the layers. Further, it is possible to reliably prevent the conductor 18 that covers the surface of the one copper foil 12 of the double-sided board 10 from being broken.

  FIG. 2 is an explanatory view showing an example of a manufacturing method of the multilayer printed wiring board 1 shown in FIG. In the manufacturing method shown in FIG. 2, the conductor 18 is formed on the surface of the copper foil 12 around the through hole 14 of the double-sided plate 10 so that the covering range is 10 to 50 μm wide from the outer periphery of the through-hole 14 of the double-sided plate 10. After coating, the single-sided plates 20 and 30 are collectively laminated on both sides of the double-sided plate 10. Specific examples of the production procedure in this case include, for example, procedures shown in the following (1) to (15).

<Processing of the first single-sided plate 20>
(1) A circuit is formed on the copper foil 22 of the first single-sided plate 20 to form the first circuit L1.
(2) The through hole 23 is drilled from the insulating base 21 side of the first single-sided plate 20 using a CO ₂ laser.
(3) A small hole 25 for air escape is drilled from the copper foil 22 side of the first single-sided plate 20 using a YAG laser.
(4) The conductive material 24 is filled in the through hole 23 of the first single-sided plate 20 by a printing method.

<Processing of Laminated Body 2 of Second Single-Sided Plate 30 and Second Adhesive Sheet 50>
(5) A circuit is formed on the copper foil 32 of the second single-sided plate 30 to form a fourth circuit L4.
(6) The second adhesive sheet 50 is laminated on the insulating base 31 of the second single-sided plate 30.
(7) The through hole 33 of the insulating base 31 of the second single-sided plate 30 and the opening 51 of the second adhesive sheet 50 are drilled from the second adhesive sheet 50 side using a CO ₂ laser.
(8) A small hole 35 for air escape is drilled from the copper foil 32 side of the second single-sided plate 30 using a YAG laser.
(9) The conductive material 34 is filled into the through hole 33 of the second single-sided plate 30 by a printing method.

<Processing of Laminated Body 3 of Double-Sided Plate 10 and First Adhesive Sheet 40>
(10) The copper foils 12 and 13 of the double-sided board 10 are formed to form the second circuit L2 and the third circuit L3. At the same time, the opening 16 of one copper foil 12 is also formed. (11) On the one copper foil 12 of the double-sided board 10, a first adhesive sheet 40 having an opening 41 previously formed is laminated. The first adhesive sheet 40 is aligned so that the opening 16 of one copper foil 12 is positioned at the center of the opening 41 of the first adhesive sheet 40.
(12) The through hole 14 of the insulating base material 11 of the double-sided board 10 is drilled from the first adhesive sheet 40 side using a CO ₂ laser.
(13) A small hole 17 for air escape is drilled from the other copper foil 13 side of the double-sided board 10 using a YAG laser.
(14) Fill the through hole 14 of the double-sided board 10 with the conductive material 15 by a printing method. At the same time, the conductive material 18 is also coated on one copper foil 12.

<Batch lamination>
(15) The surface on the insulating base 21 side of the first single-sided plate 20 and the surface on the adhesive sheet 40 side of the laminate 3, the surface on the adhesive sheet 50 side of the laminate 2 and the copper foil 13 side of the laminate 3 The two surfaces are opposed to each other and laminated together.

  FIG. 3 is an explanatory view showing another example of the method for manufacturing the multilayer printed wiring board 1 shown in FIG. In the manufacturing method shown in FIG. 3, the covering area of the through-hole 23 of the single-sided plate 20 is around the through-hole 23 of the single-sided plate 20 at a position facing the surface of the copper foil 12 around the through-hole 14 of the double-sided plate 10. After covering the conductive material 18 so as to have a width of 10 to 50 μm from the outer periphery, the single-sided plates 20 and 30 are laminated together on both sides of the double-sided plate 10, and the conductive material 18 is placed around the through hole 14 of the double-sided plate 10. It is made to contact on the surface of the copper foil 12. Specific examples of the production procedure in this case include, for example, procedures shown in the following (1) to (15).

<Processing of Laminated Body 4 of First Single-Sided Plate 20 and First Adhesive Sheet 40>
(1) A circuit is formed on the copper foil 22 of the first single-sided plate 20 to form the first circuit L1.
(2) On the insulating base material 21 of the 1st single-sided board 20, the 1st adhesive sheet 40 in which the opening part 41 was formed previously is laminated.
(3) The through hole 23 of the insulating base material 21 of the first single-sided plate 20 is drilled from the first adhesive sheet 40 side using a CO ₂ laser.
(4) A small hole 25 for air escape is drilled from the copper foil 22 side of the first single-sided plate 20 using a YAG laser.
(5) The conductive material 24 is filled in the through hole 23 of the first single-sided plate 20 by a printing method.
At the same time, the conductive material 18 is also coated on the first single-sided plate 20.

<Processing of Laminated Body 2 of Second Single-Sided Plate 30 and Second Adhesive Sheet 50>
(6) A circuit is formed on the copper foil 32 of the second single-sided plate 30 to form a fourth circuit L4.
(7) The second adhesive sheet 50 is laminated on the insulating base 31 of the second single-sided plate 30.
(8) The through holes 33 of the insulating base 31 of the second single-sided plate 30 and the openings 51 of the second adhesive sheet 50 are drilled from the second adhesive sheet 50 side using a CO ₂ laser.
(9) A small hole 35 for air escape is drilled from the copper foil 32 side of the second single-sided plate 30 using a YAG laser.
(10) The conductive material 34 is filled in the through hole 33 of the second single-sided plate 30 by a printing method.

<Processing of double-sided board 10>
(11) The copper foils 12 and 13 of the double-sided board 10 are formed to form the second circuit L2 and the third circuit L3. At the same time, the opening 16 of one copper foil 12 is also formed.
(12) The through hole 14 of the insulating base material 11 of the double-sided board 10 is drilled from one copper foil 12 side using a CO ₂ laser.
(13) A small hole 17 for air escape is drilled from the other copper foil 13 side of the double-sided board 10 using a YAG laser.
(14) Fill the through hole 14 of the double-sided board 10 with the conductive material 15 by a printing method.

<Batch lamination>
(15) The surface on the adhesive sheet 40 side of the laminate 4 and the surface on the one copper foil 12 side of the double-sided plate 10, and the surface on the adhesive sheet 50 side of the laminate 2 and the surface on the copper foil 13 side of the double-sided plate 10 Make them face each other and stack them together. At this time, the conductive material 18 coated on the first single-sided plate 20 contacts the surface of the copper foil 12 around the through hole 14 of the double-sided plate 10, and the conductive material 18 is copper foil around the through hole 14. 12 surfaces are coated.

As described above, the multilayer printed wiring board of the present invention can be obtained by forming the conductor 18 covering the surface of the copper foil 12 on the double-sided board 10 in advance and then performing batch lamination with the single-sided boards 20 and 30. Manufacture is also possible by covering the surface of the copper foil 12 of the double-sided board 10 with the conductor 18 coated around the through hole 23 of the single-sided board 20 at the same time as the batch lamination.
In the present invention, it is essential that the width w of the conductive material 18 covering the surface of the copper foil 12 of the double-sided board 10 is in the range of 10 to 50 μm, and the copper foil 12 around the through hole 14 covers the land. If formed, the land width need not be the same diameter as the width w of the conductor 18. The land width is preferably wider than the width w of the conductor 18 (in other words, the width w of the conductor 18 is narrower than the land width).

Hereinafter, the present invention will be specifically described with reference to examples. In addition, this invention is not limited only to these Examples.
In this example, a multilayer printed wiring board 1 having the configuration shown in FIG. 1 was manufactured. However, when the coating width as a comparative example was 0 μm (no coating), a multilayer printed wiring board 200 having the configuration shown in FIG. 7 was produced.

(Circuit pattern)
The circuit pattern was a daisy chain pattern (land diameter 300 μm, through hole diameter 100 μm, land-to-land pitch 600 μm, number of holes 3000 holes).

(Board configuration)
As the single-sided plates 20 and 30, the insulating base materials 21 and 31 are polyimide (thickness 25 μm), and copper foils 22 and 32 (thickness 18 μm) are provided on one side via an unillustrated adhesive (thickness 10 μm). Adopted single-sided CCL with bonded.
As the double-sided board 10, the insulating base material 11 is polyimide (thickness 25 μm), and copper foils 12 and 13 (thickness 18 μm) are bonded to both sides via an adhesive (not shown) (thickness 10 μm). Adopted double-sided CCL.
As the adhesive sheets 40 and 50, TFA-890 (thickness 25 μm) manufactured by Kyocera Chemical was adopted.

(Conductive material)
DW-250H-5 manufactured by Toyobo was used as the conductors 15, 24, 34 filled in the through holes 14, 23, 33 and the conductor 18 covering the copper foil surface. The coating thickness of the conductive material 18 was about 25 μm. 100 pieces of substrate samples were prepared in which the coating width w from the outer periphery of the through hole of the conductive material 18 was a value in the coating range shown in Table 1. Since the sample was manufactured by the above-described manufacturing method described with reference to FIG. 2, redundant description is omitted in this embodiment.

(Substrate evaluation method)
HAST (Highly-Accelerated Temperature and Humidity Stress Test) is known as a reliability test method for electronic components such as wiring boards and semiconductor devices. JEDEC (Electronic Device Technology Federation) (HAST standard # 22-A110). Therefore, in this evaluation, the same HAST standard was adopted to perform an evaluation test of the substrate.

  Using an unsaturated pressure cooker, the completed substrate was treated under HAST conditions (120 ° C./85% RH) for 24 hours, followed by gas phase thermal shock treatment (temperature cycle of −55 ° C. to 120 ° C., 60 minutes / cycle, 1000 cycles), and the conduction resistance value before and after the finished substrate was measured. Since the measurement accuracy guarantee value of the used conduction resistance measurement device was ± 2%, some trouble occurred in the sample in which the conduction resistance value after treatment increased by 5% or more compared to the conduction resistance value before treatment. It was determined that the product was defective, and this was defined as a defective product, and the defective rate (%) was counted. In addition, regarding the item of coating breakage (%), samples in which breakage of the conductive material 18 covering the copper foil surface occurred in the samples after the treatment under the HAST condition were counted. The number of samples was evaluated for 100 pieces each.

(Evaluation results)
As is apparent from the results shown in Table 1, the covering range of the conductive material 18 covering the surface of the copper foil 12 of the double-sided board 10 is 10 to 50 μm wide (however, the width is from the outer periphery of the through hole 14 of the double-sided board 10. ), Both the defect rate and the coating tear were 0%, confirming that it was extremely suitable. Further, when the coating was not broken, no rust was observed on the metal part, but when the coating was broken, some metal parts were rusted.
From the above test results, it is understood that an excellent multilayer printed wiring board with improved reliability can be obtained by setting the covering range to a range of 10 to 50 μm in the present invention.

  The present invention can be suitably used as a multilayer printed wiring board mounted on various electronic devices and a manufacturing method thereof.

It is a fragmentary sectional view showing an example of the multilayer printed wiring board of the present invention. It is explanatory drawing which shows an example of the manufacturing method of the multilayer printed wiring board of FIG. It is explanatory drawing which shows another example of the manufacturing method of the multilayer printed wiring board of FIG. It is a fragmentary sectional view which shows the modification of the multilayer printed wiring board of this invention. It is a fragmentary sectional view showing an example of the conventional multilayer printed wiring board. It is explanatory drawing which shows an example of the manufacturing method of the multilayer printed wiring board of FIG. It is a fragmentary sectional view which shows the other example of the conventional multilayer printed wiring board. It is explanatory drawing which shows an example of the manufacturing method of the multilayer printed wiring board of FIG.

Explanation of symbols

w ... Cover width of conductive material, 1 ... Multilayer printed wiring board, 5 ... Multilayer printed wiring board, 10 ... Double-sided board, 12 ... Copper foil, 13 ... Copper foil, 14 ... Through hole, 15 ... Conductive material, 18 ... Copper Conductive material covering the foil surface, 20 ... single-sided plate, 22 ... copper foil, 23 ... through hole, 24 ... conductive material, 30 ... single-sided plate, 32 ... copper foil, 33 ... through hole, 34 ... conductive material.

Claims (3)

A multilayer printed wiring board in which at least one single-sided board is laminated on each side of the double-sided board,
A multilayer printed wiring characterized in that a conductive material is coated on the surface of the copper foil around the through hole of the double-sided board, and the covering range of the conductive material is 10 to 50 μm wide from the outer periphery of the through-hole of the double-sided board Board. A method for producing a multilayer printed wiring board in which at least one single-sided board is laminated on both sides of a double-sided board,
After covering the surface of the copper foil around the through hole of the double-sided plate with a conductive material so that the covering range is 10 to 50 μm wide from the outer periphery of the through-hole of the double-sided plate, at least one sheet on each side of the double-sided plate A method for producing a multilayer printed wiring board, characterized in that single-sided boards are laminated together. A method for producing a multilayer printed wiring board in which at least one single-sided board is laminated on both sides of a double-sided board,
The conductive material was coated around the through-hole of the single-sided plate at a position facing the copper foil surface around the through-hole of the double-sided plate so that the covering range was 10 to 50 μm wide from the outer periphery of the through-hole of the single-sided plate. And then laminating at least one single-sided board on both sides of the double-sided board, and bringing the conductive material into contact with the copper foil surface around the through-hole of the double-sided board. Manufacturing method.

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